This invention relates to a method for decreasing intestinal cholesterol and fatty acid absorption in man and, specifically, to inhibiting or decreasing intestinal cholesterol and fatty acid absorption by oral administration of synthetic sulfated polysaccharides which inhibit pancreatic cholesterol esterase. The invention is based upon our discovery of sulfated polysaccharides which are potent inhibitors of human pancreatic cholesterol esterase, the enzyme responsible for promoting the intestinal absorption of cholesterol and fatty acids derived from their esterified dietary forms. The invention is also based on our observation that such agents are stable and are bioavailable to the intestine when delivered in baked goods such as biscuits and can therefore be administered in food products.
Atherosclerosis is the leading cause of death in the United States and high serum cholesterol concentrations are associated with increased risks of fatal atherosclerosis events, J.A.M.A., 53 2094 (1985) (NIH Consensus Panel). In 1988, a Consensus Panel of experts at the National Institute of Health stated that a major public health priority was the reduction of cholesterol, and that the goal of front line therapy should be to diminish the intestinal absorption of cholesterol, either through eating less cholesterol or through the use of drugs which act in the intestine to reduce cholesterol levels, Arch Inst. Med., 148, 36 (1988) (Consensus Full Report). Currently, the principal drug to inhibit cholesterol absorption is cholestyramine, a bile acid sequesterant. "Agents to Treat Hyperlipidemia", The AMA Drug Evaluations, 6th Ed., p. 903. This agent binds bile salts within the intestinal lumen, and the resulting complex is excreted in the feces. Since bile acid is not reabsorbed, the liver uses additional cholesterol to synthesize more bile which effectively lowers the sterol concentration in the body. Bile salt sequesterants are effective in lowering cholesterol, but they seldom reduce serum cholesterol by more than 15%, and they are poorly tolerated by patients. Large quantities of these ion exchange resins must be ingested (15 g or more), which lead to assaults on both the gustatory senses and intestinal function. Common side effects are constipation and bloating J.A.M.A., 253. 2095 (1985).
Cholesterol esterase is secreted by the pancreas after eating and is active in hydrolyzing ingested dietary esters of cholesterol. The enzyme is essential for absorption of cholesterol. If enzyme activity is removed from pancreatic juice, no cholesterol absorption occurs. If the cholesterol esterase activity is returned, absorption of cholesterol occurs. Borja et al., Am. J. Physiol., 206. 223 (1964) and Vahouny and Treadwell; Proc. J. Exp. Biol. and Med., 116, 496 (1964). In man, the 100 kiloDalton (kDa) molecular weight protein responsible for hydrolyzing cholesterol esters is also the principal triglyceride lipase in the pancreas. Bosner, et al., Clin. Res., 37, 366A (1989). Since fatty acids are also important in the genesis of atherosclerosis, the enzyme cholesterol esterase is essential in the intestinal absorption of those lipids responsible for producing atherosclerosis.
Despite this key role and the stated mission of the NIH to target strategies of diminishing cholesterol absorption from the intestine, no systematic study of inhibition of human pancreatic cholesterol esterase has been performed. In fact, few studies have focused on the human enzyme at all, with most attention directed to other mammalian enzymes (rat, pig, and cow) Calame et al., Arch. Biochem. Biophys., 168, 57 (1975); Van den Bosch et al., Biochem. Biophys. Acta., 286, 94 (1973); Momsen et al., Biochem. Biophys. Acta., 486, 103 (1977); Guy et al., Eur. J. Biochem., 117, 457 (1981); and Sutton et al., Biochem. Biophys. Res. Commun., 134, 386 (1986). Thus, there has been an important and continuing need to discover inhibitors of human pancreatic cholesterol esterase. The pharmacology of various sulfated polysaccharides has been investigated. Cook and Cammarata, Arch. Intern. Pharmacodyn., 144, 1 (1963). In particular, sulfated amylopectin has been taught in U.S. Pat. No. 4,150,110 as an antiulcer agent, but its properties as a cholesterol esterase inhibitor, which decrease absorption of cholesterol, have not been recognized. Sulfated dextran has been identified as an antiulcer agent, Am. J. Surgery, 113, 27 (1967). This compound has been recognized for use in the treatment of hyperlipemia and as an orally administered anticoagulant, British Patent No. 953,626. In addition, certain sulfated dextrans, specifically those of low molecular weight (7000-8000, 7-8 kDa), have been shown to reduce serum cholesterol levels at a dose of 1800 mg/day. Goro et al., J. Clin. Biochem. Nutr. 2:55-70 (1987).